Heretofore, a visor structure has been provided for the cab of a harvester. One such structure is shown in U.S. Pat. No. 4,185,867, issued Jan. 29, 1980, to William M. Schmidt, Stanley E. Thorwaldsen, David C. McElroy and Stephen G. Miggels for a "Harvester with a Laterally Extending Visor Structure". The visor structure shown in U.S. Pat. No. 4,185,867 includes portions secured to the cab roof which extend forwardly and laterally to each of the opposite sides of the cab roof except in the area of the cab door. The air conditioning apparatus, including the air filter, air passageways, heater and cooler, is contained in the cab rather than in the visor parts added to the cab. The prior art visor structure is used to mount operating lights and rear view mirrors. U.S. Pat. No. 3,868,896 shows a forced air ventilating system in the top of a tractor cab and U.S. Pat. No. 4,189,987 illustrates a temperature control system for a tractor cab with environmental components in the roof.